ISL281X7SOICEVAL1Z Datasheet, PDF (1/4 Pages) Intersil Corporation – Evaluation Board User’s Guide

Application Note 1508
ISL281X7SOICEVAL1Z Evaluation Board User’s Guide
Introduction
The ISL281X7SOICEVAL1Z evaluation board is a design
platform containing all the circuitry needed to
characterize critical performance parameters of the
ISL281X7 operational amplifiers in SOIC-8 package,
using a variety of user defined test circuits.
The ISL281X7 operational amplifiers feature low bias
current, low noise, and low offset and temperature drift.
Reference Documents
• ISL28107 Data Sheet, FN6631
• ISL28117 Data Sheet, FN6632
• ISL28127 Data Sheet, FN6633
Evaluation Board Key Features
The ISL281X7SOICEVAL1Z is designed to enable the IC
to operate from a single supply, +4.5VDC to +40VDC or
from split supplies, ±2.25VDC to ±20V. The board is
configured for a single op amp connected for differential
input with a closed loop gain of 10. A single external
reference voltage (VREF) pin and provisions for a
user-selectable voltage divider-filter are included.
Power Supplies (Figure 1)
External power connections are made through the +V, -V,
VREF and Ground connections on the evaluation board.
For single supply operation, the -V and Ground pins are
tied together to the power supply negative terminal. For
split supplies, +V and -V terminals connect to their
respective power supply terminals. De-coupling
capacitors C2 and C4 connect close to their respective
supplies, while two additional capacitors, C1 and C5, are
connected close to the part to filter out high frequency
noise. Anti-reverse diodes D1 and D2 protect the circuit
in the case of accidental polarity reversal.
V-
V+
VREF
C2
4.7µF
D1
S1AB
C4
4.7µF
D2
S1AB
FIGURE 1. POWER SUPPLY CIRCUIT
Amplifier Configuration (Figure 2)
The schematic of 1/2 of the op-amp with the components
supplied is shown in Figure 2. The circuit implements a
differential input amp with a closed loop gain of 10. The
circuit can operate from a single supply or from dual
supplies. The VREF pin must be connected to ground to
establish a ground referenced input for dual supply
operation, or can be externally set to any reference level for
single supply operation. VREF should not be left floating.
IN-
IN+
VCM
IN -
IN +
VREF
RIN-
10kΩ
RIN+
10kΩ
RF
100kΩ
VP
IN- _-
V+
V-
IN+ ₊
VM
RREF+
100kΩ
ISL281X7
0Ω
VOUT
RL
DNP
VREF GND
FIGURE 2. BASIC AMPLIFIER CONFIGURATION
November 9, 2009
AN1508.0
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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